Well string cutting apparatus

Abstract

A well cutting tool for cutting casing in a well bore having a cutter body and at least one cutting arm pivotally mounted in a longitudinally extending slot of the cutter body. The cutting arm has removable and replaceable cutting inserts positioned along its outer front surface and its lower end surface. A removable and replaceable projection on the upper end of the cutter arm is provided for contact by a fluid pressure actuated piston for outward pivoting of the cutter arm into cutting position.

What is claimed is: 
     
       1. A well cutting tool for cutting well casing comprising: a tubular cutter body having a longitudinally extending slot therein and adapted to be connected to a well string for being lowered into a well;   an elongate cutter arm received within said slot and having a cutting surface adjacent its lower end;   means on the cutter body for pivotally securing the upper end of said cutter arm in said slot to permit the outward pivoting of the lower end of the arm into cutting contact with the casing;   a piston in said cutter body movable longitudinally of said cutter body in response to fluid pressure in said well string, means continuously urging the piston in an upward direction;   a replaceable projection on said cutter arm having an end with a rounded surface thereon in a position to be engaged by said piston upon downward movement thereof in response to an increase in fluid pressure in the well string thereby to cause the lower end of said arm to pivot outwardly into cutting position with said well casing, said projection having a stem extending from said end, said arm having a recess into which said stem is received; and   means for removably securing said projection within said recess thereby to permit said projection to be easily replaced.   
     
     
       2. A well cutting tool as set forth in claim 1 wherein said cutter arm has a removable cutting insert adjacent its lower end, said cutting insert having a base removably secured to said arm and a cutting material secured to the base along an outer surface thereof for contacting the casing in cutting relation. 
     
     
       3. A well cutting tool for cutting well casing comprising: a tubular cutter body having a longitudinally extending slot therein and adapted to be connected to a well string for being lowered within the well casing;   an elongate cutter arm received within said slot and having a cutting surface adjacent its lower end;   means on the cutter body for pivotally securing the upper end of said cutter arm in said slot to permit the outward pivoting of the lower end of the arm into cutting contact with the casing;   means to contact said cutter arm under a predetermined condition to move the lower end of said arm radially outwardly into cutting contact with the casing;   a plurality of replaceable cutting inserts in longitudinally aligned relation along the outer front surface of said elongate cutter arms forming a continuous cutting surface; and   means removably mounting each of said plurality of cutting inserts on said outer front surface of said elongate arm to permit individual replacement of said cutting inserts.   
     
     
       4. A well cutting tool as set forth in claim 3 wherein each of said replaceable cutting inserts comprises a base removably secured to said arm and a cutting material along an outer surface of the base for contacting the casing in cutting relation. 
     
     
       5. A well cutting tool as set forth in claim 4 wherein said arm and said base have an interfitting dovetail groove and projection for removably securing the inserts on the arm. 
     
     
       6. A well cutting tool for cutting well casing comprising: a tubular cutter body having a longitudinally extending slot therein and adapted to be connected to a well string for being lowered within the well casing;   an elongate cutter arm received within said slot and having a cutting surface adjacent its lower end;   means on the cutter body for pivotally securing the upper end of said cutter arm in said slot to permit the outward pivoting of the lower end of the arm into cutting contact with the casing;   means to contact said cutting arm under a predetermined condition to move the lower end of said arm radially outwardly into cutting contact with the inner periphery of the casing;   a plurality of replaceable cutting inserts arranged in longitudinally aligned sections along the outer front surface of said elongate cutter arm to form a continuous elongate surface, each insert having a base removably secured to said arm and a cutting material along an outer surface of the base for contacting the casing in cutting relation; and   means for releasably securing said base on said arm, and permitting selective replacement of individual cutting inserts on said arm.   
     
     
       7. A well cutting tool as set forth in claim 6 wherein said arm and said base have an interfitting dovetail connection and a locking screw releasably securing said base to said arm at said dovetail connection. 
     
     
       8. A well cutting tool as set forth in claim 6 wherein a removable corner insert extending along the lower end surface of said arm is positioned at the lower end of said arm.